The logistics of bulk storage and transport of goods and materials require an effective and efficient use of storage space. Known pallet racking offers the ability to store items using ever increasing capacities of vertical space up to the height and depth of the racks own dimensions. Adjustable pallet racking (APR) is the most common type of pallet racking system in use throughout the world. APR is a skeletal system of vertical, diagonal and horizontal interconnecting steel members. APR installations are usually constructed with a one pallet deep run of racking on either side of an operating aisle. If the racks can only be accessed from one side only by Mechanical handling equipment (MHE) then this is called a single entry run. If the racks can be accessed from both sides then this is called a double entry run.
Referring to FIG. 1 herein, known racking 100 consists usually of two major components, upright frames and beams. Upright frames 101 are assembled using pairs of continuously perforated uprights 102,103 connected by bracing members 104,105 with bolted, riveted or welded joints.
Upright frames are interconnected by beams 106,107 in pairs to form a row of bays as shown in FIG. 2 herein. Pairs of beams 200,201 are spaced apart vertically in each bay at a number of levels to provide locations for the pallet or unit loads. Each pair of beams at each level can carry one, two or more unit loads depending on its length and strength. The strength, stiffness and stability of the racking is provided by the upright frames and their connections 202 to the concrete floor slab, both of which must be maintained within the manufacturer's operating parameters in order to be safe.
In general, pallet racking is arranged to maximize the usage of available storage space, which means that the aisle spacing between adjacent runs of pallet racking is kept to a minimum consistent with achieving access to the racking for loading or unloading of the racking. By the very nature of its designed task, a mechanical handling equipment (MHE), such as a fork lift truck, must operate and maneuver within very close proximity to pallet racking equipment in order to transit, store and retrieve unit loads between and within the racks structure respectively. During these operations, there is a likelihood destructive dynamic impact forces between the moving MHE and the pallet racking may occur.
Damaged racking uprights have specific tolerances within which they must operate in order for them to be used safely. The upright and bracing sections of a racking frame are designed for bearing a vertical load. Lateral impacts can have severe safety and financial loss potential. The recommendations given in the Storage Equipment Manufacturer's Association (S.E.M.A) Code of Practice is considered within the storage industry as the safe minimum standard with which to measure the safe condition of racking. These recommendations include:                ‘For an upright bent in a lateral direction from its front, a vertical concave dent exceeding 5 mm over a 1000 mm plane of measurement is considered dangerous and should be decommissioned and replaced.’        ‘For an upright bent in the plane of the frame bracing, a vertical dent exceeding 3 mm over a 1000 mm plane of measurement is considered dangerous and should be decommissioned and replaced.’        ‘For an upright which has been damaged such that there is a simultaneous bend in both longitudinal and lateral directions the left or right and front to back deformation shall be measured separately . . . and the appropriate limits observed’.        
Although dominated by vision, operating an MHE is a highly cognitive task. It usually occurs in a visually cluttered environment, requires the simultaneous use of central and peripheral vision and involves relatively complex MHE-control activities. While functional differences between the central and peripheral visual fields are well documented, the linkage between the two is less understood. In a typical test of the visual field, the operator fixates on the point where the raised palletized load is situated. Thus, a standard visual test cannot predict how efficiently an operator can use peripheral visual information in complex tasks such as operating MHE. Peripheral retinal sensitivity, under photopic and mesopic (artificial) lighting conditions, (such as is found in a typical warehouse environment) is considerably reduced compared to the central retina. This means that for an object to be seen peripherally it would need to be of higher intensity than if it was to be detected centrally. This can easily be attributed to the distribution characteristics of the human photoreceptors (rods and cones) on the retina. It has been shown that peripheral retinal sensitivity may be impeded as the amount of information the subject is required to process mentally is increased. This visual field “narrowing” applies to the warehouse environment and other tasks, such as the simultaneous controlling of speed and direction of the MHE and its load, navigating with aisle signs and using in-MHE information systems.
As a consequence, important visual stimuli in the periphery of a person's vision may remain undetected when cognitively demanding tasks involving central vision are being performed. Thus, the proximity of the MHE to the vulnerable lower sections of an upright section is difficult to monitor in a manner that is reasonably practicable and the risk of impacts occurring increases. Invariably, such damage has direct costs to an organization's resources. Warehouse maintenance may absorb an average of only five percent of total warehouse costs but any neglect of the issues can have cost consequences far beyond that fraction. Damage to racking incurs both direct costs (e.g. component replacement and labor costs, damaged stock, damaged MHE, accidents and incidents) and indirect costs (e.g. reduced storage capacity, administration costs, employee absence, litigation, increased insurance premium, adverse publicity and overall disruption of business).
One type of known column protector comprises a metal shield which is bolted to the, typically concrete, floor at the base of a column, and shields the column from impact by transmitting the impact force down through the floor, and having an air gap between the metal shield and the column. However, such column protectors require penetrating expansion bolts, which compromise the integrity of the concrete floor, and over time are subject to degrading or working loose. Further, on impact, they are prone to buckling and bending, or the bolts are ripped out of the concrete when subject to impact from a vehicle or MHE. They are also time consuming to replace when damaged, and replacement can be made more difficult where the bolts have sheared or bent, or have damaged the concrete floor. Replacement of a single protector can take up to 25 minutes. Examples of such protectors are found in U.S. Pat. No. 5,369,925.
Another type of column protector comprises a single piece molded plastics shroud, having a flat outer face and straight side portions connected by rounded portions so as to form a substantially “U” shaped single piece member which protects one side of a column post. Such protectors are fitted around a column by tensioned wire straps or bands and protect one side of the column. Where all round protection of the column or post is required, two such protectors can be fitted back to back around the post, and retained by longer wire straps or bands. However, this type of protector is bulky because it relies on a single molded piece to absorb all impact forces, and therefore that molded piece has to be relatively thick. This means that the rack needs to be spaced further apart to allow access for vehicles and mechanical handling equipment. Additionally, removal of the protectors for inspection of the column requires cutting of the straps and fitting new straps. With this type of know protector, serious damage to a column after an impact can go undetected because removal of the protector is not easy. An example of this type of impact protector is disclosed in U.S. Pat. No. 6,242,070.
Another type of known column protector comprises a rigid square or rectangular outer shell, a first and resilient inner lining, and a second resilient inner lining intermediate between the outer shell and the first inner lining. The inner lining wraps around a column, and closely fits the column. They are attached to the column by means of ties or straps between the free edges of the outer shell at the rear of the protector. The outer and inner shells are shaped to be rectangular or square, fitting around the substantially rectangular outward facing portions of the columns. Such column protectors are inefficient at dissipated impact forces due to their shape, having outer surfaces which lie parallel to the surfaces of the underlying columns, and act to transfer impact forces undeflected, in a direction directly to the underlying columns. They also suffer from the problem of splitting at their edges when subjected to impact. Additionally, their removal and replacement generally requires tools and new wires, ties or straps to attach the protector to the racking column upright, which in turns dissuades inspection of the parts of the column which are hidden from view by the protectors. Significant damage to the hidden parts of the columns can go undetected.